Field
Embodiments of the present disclosure relate generally to methods and apparatus for use in association with lighting systems.
A batwing shaped light distribution may be preferred in various lighting applications, for example, illuminating streets, outdoor areas, pedestrian crossings, roundabouts, garages, rooms and commercial stores. FIG. 1 is a cross-sectional view of a prior art lighting system 100 that produces a batwing shaped light distribution to illuminate an area 102 (e.g., a portion of a street). The system 100 includes a light source 104, which may be disposed on a substrate 106. The light source 104 includes a light emitting diode (LED) 108 or other source of light. The LED 108 or other source of light may be disposed in a package, e.g., an LED package 110, which includes a light transmitting case, e.g., case 112, and the LED 108 or other source of light mounted or otherwise disposed therein. The system 100 further includes a lens 114 and a light transmitting cover 116. In operation, the light source 104 produces light, represented in part by a light ray 120, which passes through the case 112 (if included), the lens 114 and the cover 116 to result in a batwing shaped light distribution.
Brief Description
It has been determined that a significant portion of the light 120 that passes through the lens 114 will strike the surface of the cover 116 at an angle 122 (shown in FIG. 1B, relative to a normal line 124) (sometimes referred to as an angle of incidence) that is large enough to cause a significant percentage of the light to be reflected, e.g., represented in part by light ray 126, off the cover 116, rather than transmitted, represented by the light ray 120, through the cover 116, thereby significantly reducing the efficiency of the lighting system 100. It has also been determined that the percentage of light that will be reflected off the cover, rather than transmitted through the cover, could be reduced (thereby increasing efficiency), while still providing a batwing shaped light distribution, if a geometry of the lens and a geometry of the cover are made complementary, in certain respects. As used herein, the term “complementary” means complementary to at least some degree.
It has also been determined that the percentage of light that will be reflected off a cover, rather than transmitted through the cover, could be reduced (thereby increasing efficiency), in applications that do not employ a batwing shaped light distribution, if a geometry of the lens and a geometry of the cover are made complementary, in certain respects.
In a first aspect, a lighting system comprises: a light source and a lens spaced apart from the light source by a first gap. The lens includes a first surface to receive light from the light source. The lens further includes a second surface through which at least a portion of the light received by the first surface of the lens exits the lens. The lighting system further comprises a cover spaced from the lens by a second gap. The cover includes a first surface to receive at least a portion of the light that exits the lens. The cover further includes a second surface through which at least a portion of the light received by the first surface of the cover exits the cover. The second surface of the lens includes a convex portion that is convex with respect to the light source. The first surface of the cover includes a convex portion that is convex with respect to the light source and disposed over the convex portion of the second surface of the lens. The second surface of the lens further includes a first concave portion that is concave with respect to the light source. The first surface of the cover further includes a first concave portion that is concave with respect to the light source and disposed over the concave portion of the second surface of the lens. In some embodiments, the second surface of the cover is flat.
In some embodiments, the at least a portion of the light that exits the cover through the second surface of the cover has a batwing shaped light distribution. In some embodiments, the first surface of the lens faces toward the light source, and the second surface of the lens faces toward the first surface of the cover. In some embodiments, the convex portion of the first surface of the cover receives the convex portion of the second surface of the lens, at least in part. In some embodiments, the convex portion of the first surface of the cover includes two convex portions that are convex with respect to the light source, the first concave portion of the first surface of the cover is disposed between the two convex portions, the convex portion of the second surface of the lens includes two convex portions that are convex with respect to the light source, the first concave portion of the second surface of the lens is disposed between the two convex portions of the convex portion of the second surface of the lens.
In some embodiments, the first surface of the cover further includes a second concave portion that is concave with respect to the light source, the second concave portion of the first surface of the cover includes two concave portions that are concave with respect to the light source, the convex portion of the first surface of the cover is disposed between the two concave portions, the second surface of the lens further includes a second concave portion that is concave with respect to the light source, the second concave portion of the second surface of the lens includes two concave portions that are concave with respect to the light source, and the convex portion of the second surface of the lens is disposed between the two concave portions of the second concave portion of the second surface of the lens. In some embodiments, each of the two concave portions of the second concave portion of the first surface of the cover are disposed over a respective one of the two concave portions of the second concave portion of the second surface of the lens.
In a second aspect, a method comprises spacing a lens apart from a light source by a first gap, the lens including a first surface to receive light from the light source, the lens further including a second surface through which at least a portion of the light received by the first surface of the lens exits the lens. The method further comprises spacing a cover apart from the lens by a second gap, the cover including a first surface to receive at least a portion of the light that exits the lens, the cover further including a second surface through which at least a portion of the light received by the first surface of the cover exits the cover. The second surface of the lens includes a convex portion that is convex with respect to the light source. The first surface of the cover includes a convex portion that is convex with respect to the light source. The second surface of the lens further includes a first concave portion that is concave with respect to the light source. The first surface of the cover further includes a first concave portion that is concave with respect to the light source and disposed over the concave portion of the second surface of the lens.
In a third aspect, a lighting system comprises: a light source and a lens spaced apart from the light source by a first gap. The lens includes a first surface to receive light from the light source. The lens further includes a second surface through which at least a portion of the light received by the first surface of the lens exits the lens. The lighting system further comprises a cover spaced from the lens by a second gap. The cover includes a first surface to receive at least a portion of the light that exits the lens. The cover further includes a second surface through which at least a portion of the light received by the first surface of the cover exits the cover. The second surface of the lens includes a convex portion that is convex with respect to the light source. The first surface of the cover includes a convex portion that is convex with respect to the light source and disposed over the convex portion of the second surface of the lens. The second surface of the cover is flat.